photo courtesy of Robert BeginNorwich architecture student Christy Ketchel places wooden cutouts in the shape of a tree into a fabric frame at the Yestermorrow Design/Build School in Warren, Vt. She is helped by Ronnie Araya-Caceres, another participant in the Fabric-Formed Concrete Workshop and Conference.

Christy Ketchel, dressed in work clothes, looked up an 11-foot embankment as a large cement-mixing truck poured its contents into forms for a wall of what will one day be a small cabin.

“Isn’t it great? It looks like a blow-up mattress,” she exclaimed as the forms began to fill.

Ketchel and Robert Begin, architecture students from Norwich University—the country’s oldest private military college—were among a dozen people building the wall using plastic “fabric” forms instead of the customary plywood. Molds are built from polymer cloth suspended from wooden molds. Instead of rebar, a pliable carbon-fiber mesh is used to reinforce the concrete.

Ketchel, who lives in Warren and commutes to Norwich’s campus in Northfield, said the workshop helped her understand the versatility of concrete. “I totally buy into this technique,” she said.

The wall project culminated the weeklong August 2009 Fabric-Formed Concrete Workshop and Conference sponsored by the Norwich School of Architecture & Art and Yestermorrow, a design school that specializes in environmental sustainability. The workshop attracted architects and students from various states, Canada, and even one from Denmark.

Fabric-formed concrete construction techniques have been around for decades, yet the method is still considered innovative—not quite mainstream enough for the building industry to fully embrace. Advocates, however, say the technique can cut costs while allowing architects more flexibility in their designs.

Unlike plywood forms, fabric is flexible. Designers and builders can more easily create soft curves with concrete, where sharp angles might otherwise have been required. As the wet cement mixture flows between sections of fabric it can stretch the material in odd ways, creating unpredictable but welcome textures.

Fabric-formed concrete work “allows for some wild and interesting” shapes, said Eleanor D’Aponte, an assistant professor in the architecture school who helped organize the workshop.

She said fabric is cheaper to produce, lighter and less costly to transport than plywood. Unlike plywood, she said, it can be readily reused.

“This is very exciting; we’ve been anticipating this all week,” said Ketchel during a break from her work. She and several others had been at the base of the form, gently tapping the fabric’s exterior as the wet mixture flowed in so that air pockets would not develop between fabric sheets. After about 30 days, she said, the form will be taken off and the cabin, planned at about 300 square feet, will have its first wall. It will be about 10 inches wide at the base and four inches wide at the roofline.

D’Aponte expects that students in similar workshops will complete the project over the next two summers by building three additional walls using steel and glass. The cabin will be topped by a concrete roof that may someday be covered with soil and plants. The cabin will be used as a demonstration building and living quarters for Yestermorrow’s students and visitors.

Norwich’s architecture program is dedicated to finding ways for its students to get their hands dirty, she added.

“The School of Architecture & Art is committed to the design/build process, both to give students an opportunity to work with materials and see firsthand the effects of water, wind and gravity on structures they design,” said D’Aponte. “In addition, it is a great opportunity to engage with the local community and with professionals working in the field.”

Ketchel and Begin said the workshop offered invaluable hands-on experience and that they are hooked on concrete as a building medium. The two of them, with help from other students, already had prefaced the workshop for four days designing the cabin’s first wall and building wood frames to support the fabric.

“It definitely has been fun,” said Begin, of Hardwick, Mass., who added he’s never worked with concrete except to help pour a basketball court. He likes the fact that the fabric-form method allows for a more “fluid” design. A snowboarder, he is happy to have found a medium that may one day help him design structures reflecting the exhilaration and motion of snowboarding.

“With fabric forms, we can create an entire structure out of one fluid piece,” he said.